Rat bite fever
Background
- Bacteria: Streptobacillus moniliformis - gram negative rod
- Part of the normal respiratory flora of rodents.[1]
- Spread via a rat bite, scratch, or saliva[2]
- 3-21 days post exposure
- Misdiagnosed or left untreated: 13% mortality rate.[3]
Clinical Features
- Fever
- Fatigue
- Headache
- Pharyngitis
- Nausea and vomiting
- Rash: maculopapular, though can be petechial or purpuric
- Most prominent on the extremities, palms, and soles
- Polyarticular and asymmetric arthralgias in up to 50% of patients
Differential Diagnosis
- Viral Infections
- Palms/soles rash:
- Meningococcemia/Neisseria meningitidis
- Rocky mountain spotted fever
- Hand-foot-and-mouth disease
- Syphilis
Labs
- CBC
- Electrolytes
- CRP
- LFTs
- Blood Cultures
- Notify the lab: requires enriched trypticase soy agar or broth, and request that the cultures be held for up to two weeks, as the bacteria grow very slowly.[4]
- Consider Infectious cultures: Syphilis
- Consider Isolation: Neisseria meningitidis
Management
- Difficulty to confirm the diagnosis by culture: empiric antibiotic treatment should be started immediately due to the high complication and fatality rate.
- Adults
- IV penicillin G: 200,000 units q4 hours for 5–7 days (can be switched to PO once patient shows clinical improvement)
- PO penicillin V: 500mg QID, to complete a 14-day treatment course
- Doxycycline (for PCN-allergic patients): IV or PO 100mg BID for 14 days
- Pediatrics
- IV penicillin G: 100,000–150,000 units/kg/day, divided in 4 doses, up to maximum 8 million units/day, for 5–7 days (can be switched to PO once patient shows clinical improvement)
- PO penicillin V: 25–50mg/kg/day, divided in 4 doses, up to maximum 2g/day, to complete a 14-day treatment course
- Doxycycline (for PCN-allergic patients): 2–4mg/kg/day IV or PO, divided in 2 doses, for 14 days
References
- ↑ Pickering LK, Baker CJ, Kimberlin DW, et al. Red book: 2009 report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, Ill: American Academy of Pediatrics; 2009:299-300.
- ↑ Rat-Bite Fever’s Non-Specific Symptoms Make Patient History Important for Diagnosis. Vetter N. March 16, 2015. http://www.acepnow.com/article/rat-bite-fevers-non-specific-symptoms-make-patient-history-important-for-diagnosis/
- ↑ US Department of Health and Human Services. Rat-bite fever (RBF). 2012. Available at: www.cdc.gov/rat-bite-fever/health-care-workers/index.html. Accessed Feb. 16, 2015.
- ↑ Elliott SP. Rat bite fever and Streptobacillus moniliformis. Clin Microbiol Rev 2007;20:13-22.
Case Reports
- Ojukwu IC1, Christy C. Rat-bite fever in children: case report and review. Scand J Infect Dis. 2002;34(6):474-7.
- Sean P. Elliott et al. Rat Bite Fever and Streptobacillus moniliformis Clin Microbiol Rev. 2007 Jan; 20(1): 13–22. doi: 10.1128/CMR.00016-06 PMCID: PMC1797630